Title: Strong, Self-healing Hydrogel Created for Tissue Engineering

Researchers from the University of Tokyo have created a strong, self-healing hydrogel that has applications in tissue engineering and drug delivery. The hydrogel was created by adding sodium polyacrylate and the researchers' "G binder" to a combination of clay disks and water. The binder was made from long chains of polyethylene glycol, a common ingredient in skin care. The researchers, led by Takuzo Aida and Justin Mynar from the University of Tokyo, published their findings in the Jan. 21, 2010, edition of Nature.

According to the report, after small, thin clay disks are added to water, the disks are dispersed with sodium polyacrylate, which wraps around the positively charged edges and prevents the disks from clumping. Then the solution is shaken for a few minutes, the binder is added, and the solution is shaken again.

The binder is reportedly designed with branched ends that are positively charged to adhere to the negatively charged surface of the clay, resulting in a stiff gel. The ability of the hydrogel to heal comes from the binder's guanidinium. The end of the binder's long polyethylene glycol chains hosts multiple branches tipped with guanidium, a molecular building block of DNA and RNA. These branching arms allow the hydrogel to heal itself by grabbing surrounding clay.

The researchers report that the hydrogel is compatible with biologically important molecules, having combined the gel with myoglobin and retained 70% of the molecule's activity. Additionally, the hydrogel has a number of uses that the researchers are exploring. For instance, it can by injected into the body or used in the laboratory to compartmentalize biologically important molecules or set up a cascade of reactions.

While the technology has not been specified for applications in personal care, its applications in tissue engineering and delivery could be transferable for the development of animal-alternative test methods and improve the delivery of cosmetic actives, respectively.